Capacity of digital cellular TDMA systems

The capacity of digital TDMA (time-division multiple-access) systems is addressed. It is projected that capacity improvement will be of the order of 5-10 times that of analog FM without adding any cell sites. For example, the North American TIA (Telecommunication Industry Association) standard offers around 50 Erlang/km/sup 2/ with a 3-km site-to-site distance. In addition, the TDMA principle allows a faster handoff mechanism (mobile assisted handoff), which makes it easier to introduce microcells with a cell radius of about 200 m. This gives substantial additional capacity gain beyond the 5-10 factor given above. TDMA makes it possible to introduce adaptive channel allocation (ACA) methods. ACA is a mechanism that provides efficient microcellular capacity. ACA also eliminates the need to plan frequencies for cells. It is concluded that the air-interface of digital TDMA cellular may be used to build personal communication networks.<
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